Leaf gas exchange of beech (Fagus sylvatica L.) seedlings in lightflecks: A system for measuring rapid changes in CO2 partial pressures.

A system is described for the measurement of fast transient responses of leaf gas exchange to lightflecks. Any chamber adulterates a true signal unless in the steady-state; therefore, a procedure for estimating an 'effective chamber volume' is presented which is an essential parameter for correcting a measured transient signal. A common correction is critically commented on. With the system, responses of net photosynthesis to lightflecks as short as 1 s have been observed in leaves of seedlings of Fagus sylvatica L.